Carboxy-substituted pimelic acids



Patented Nov. 27, 1945 CARBOXY-SUBSTITUTED P-IMELIC ACIDS Herman A. Bruson, Philadelphia, Pa.,assignor to The Resinous Products & Chemical Company, Philadelphia, Pa., a corporation of Delaware No Drawing. Application September 22, 1942, Serial No. 459,301

6 Claims. (Cl. 260-537) This invention relates to new polycarboxylic acids having the formula CEhQEaCOOH R-C-COOEI CHiCHsCOOH wherein R is a hydrocarbon or substituted hydrocarbon group.

These acids possess useful properties in the form of their esters or amides for the preparation of plastics, plasticizers, and resinous compositions.

Although -carboxy-pimelic acid,

I have found that polycarboxylic acids having the formula omcnicoou R-G-CO-GH:

cmcmcooa wherein R is a hydrocarbon or substituted hydrocarbon group, are readily converted by means of alkaline hypohalite solution to the above desired 'y-carboxy-carboxylic acids according to the reaction:

CHICHIC 0 0H NaOCl or NaOIBr R-C-C O-GH:

Execs NaOH CHICHIG 0 0H 7 C H|CH:O 0 0H R-C-COOH A +CHOh or OHBn CHaCHiC 0 0H -The 'y-acetyl-q-substituted pimelic acids, or a salt thereof, used as the starting materials are readily obtained by alkaline hydrolysis of the polycyanoethylation products derived by reacting acrylonitrile in the presence of alkali upon ketones having formulas such as RCH2-CO CH3 wherein R is hydrogen or a hydrocarbon group, as described in copending applications Serial No. 389,332, filed April 19, 1941, Serial No. 414,598, filed October 11, 1941, and Serial No. 1213M, filed December 2, 1941.

In general, the reaction between the 'y-acetyl- 'y-substituted pimelic acid or a salt thereof and alkaline hypohalite solution is performed by mix ing the two reactants between 0 C. and about 0., whereby chloroform is produced. The chloroform is readily removed or separated and the salt of the desired acid is formed, which, upon acidification with a strong acid, such as sulfuric, hydrochloric, etc., is converted to the desired 'y-carboxy-y-substituted pimelic acid.

Because of the usually high solubility of these acids, it is desirable to extract them to purify them. Some of the acids having long-chained substituents, however, may be precipitated or separated directly.

In this manner, there may be obtained, by choice of suitable ketones, acids of the formula CHrCHsCOOH R-C-COOH CHaCHaCO OH 'y-C'arbomy-y-methyZ-pimelic acid.A solution of alkaline potassium hypochlorite was prepared by stirring at 50 C. a solution of 660 grams of water and grams of calcium hypochlorlte (70% available chlorine) with a solution of 115 grams of anhydrous potassium carbonate, 33 grams of potassium hydroxide and 330 grams of water for about ten minutes and filtering of! the precipitate of calcium carbonate.

The clear filtrate was stirred, and to it was added dropwise a solution of '71 grams of 'y-acetyl- -methyl-pimelic acid in 200 grams of 20% sodium hydroxide solution while the reaction mixture was maintained at 60-'l0 C. by external cooling. Chloroform was evolved. After all of this solution had been added to the hypochlorite solution, the resulting mixture was stirred for one hour longer at 60-70 C., and any excess hypo- 'y-c'arbomy-y-ethul-pimelic acid.To a stirred filtered solution of potassium hypochlorite prepared as in Example 1 from 250 grams of calcium hypochlorite in 1,000 grams of water and a solution .of 175 grams f.K2CO3, 50 grams of KOH and 500 grams of water, there was gradually added a solution of 115 grams of 'y-acetyl- 'y-ethyl-pimelic acid in 300 grams of 20% sodium hydroxide at 60-'l0 C. Chloroform was evolved.

The mixture was stirred for eight hours longer at room temperature and was then treated with sufficient sodium bisulfite to destroy any excess of hypochlorite. The solution was acidified with 250 grams of concentrated hydrochloric .acid and evaporated to dryness in vacuum. The solid resi-'- due, upon extraction with acetone, yielded 105 grams of crystalline product upon evaporation of the acetone extract. The pure 'y-carboxy-vethyl-pimelic acid forms colorless crystalsmelting at 172 C. after recrystallization from water or nitromethane.

The -acetyl- -ethyl-pimelic acid used is a crystalline solid, melting point 112-113 0., obtainable by alkaline hydrolysis of the dicyano- .ethylation-product of methyl propyl ketone.

Example 3 'y Carbowy 'y phenyl pimelic acid-To a stirred filtered solution of potassium hypochlorite, prepared by treating grams of calcium hypochlorite in 200 cc. of water with a solution of 35 grams of K2002, 10 grams of KOH and 100 cc. of water, there was gradually added at 60-70 C. a solution of 27.8 grams of 'y-acetyl-v-phenylpimelic acid in 60 grams of aqueous 20% sodium hydroxide. Chloroiorm was evolved. The mixture was stirred for one hour longer after reaction had ceased. It was then acidified with concentrated hydrochloric acid and theolear solution evaporated to dryness in vacuum. Upon extraction of'theresidue with acetone and evaporation of the filtered extract, crude 'y-carboxy- 'y-phenyl-pimelic acid was obtained as a resinous mass which, upon recrystallization from nitrograms of KOH, and 170 grams of water.

'methane, formed colorless crystals melting at The -y-acetyl-y-phenyl-pimelic acid used as starting material is a crystalline solid, melting point 171-1'l2 C., obtainable by alkaline hydrolysis of the dicyanoethylation product of phenylacetone. Example 4 'y-Carbomy-v- (carboxy-ethyl) -pimelic acid-To a stirred suspension of 340 grams of water and 85 grams of calcium hypochlorite there was added at 50 C. a solution of 60 grams of K2COa,17 The calcium carbonate was filtered ofl. Toithe stirred filtrate, at 60-70 0., there was added dropwise a solution of 136 grams of 20% sodium hydroxide and 46.5 grams of 1,1,l-tri-(p-carboxy-ethyl)- acetone. Chloroform was evolved. The mixture was stirred for two hours after reaction had ceased. Excess of hypochlorite was destroyed with sodium bisulfit solution, and the mixture was acidified with concentrated hydrochloric acid. The clear solution obtained was evaporated to dryness in vacuumon a steam bath. The dry residue was extracted with hot acetone and the acetone extract evaporated to dryness. The 'y-carboxy-w-(carboxy-ethyl)-pimelic acid was obtained as a colorless crystalline solid melting at 192 C. after softening at 182 C.

The 1,1,1-tri-(p-carboxy-ethyl), -acetone used as starting material is a crystalline solid, melting point 149-150 C., obtainable by alkaline hydrolysi of the tricyanoetliylation product of acetone.

Example 5 'y-Carboxy-q-isopropenyl-pimelic GCid.-TO a stirred filtered solution ofpotassium hypochlorite, prepared by treating a suspension of 250 grams of calcium hypochlorite in 1,000 cc. of water at 50 C. with a solution of 175 grams of KzCOa, 50 grams of KOH and 500 cc. of water, there was added gradually at 60-'l0 C. a solution of 121 grams of 'y-acetyl-y-isopropenylpimelic acid in 300 grams of aqueous 20% sodium hydroxide. Chloroform was evolved. The mixture was stirred for three hours after reaction had apparently ceased. Excess of hypochlorite was then destroyed by adding sodium bisulfite solution. The resulting solution was acidified with concentrated hydrochloric acid and evaporated to dryness in vacuum. The dry residue was extracted with acetone. Upon evaporation of the filtered acetone extract, grams of crystalline product was obtained. After recrystallization from water, the 'y -carboxy-'y-isopropenyl-pimelic acid formed colorless crystals melting at C.

The 'y-acetyl-y-isopropenyl-pimelic acid used as starting material is a crystalline solid, melting point 136l37 C., obtainable by alkaline hydrolysis of the dicyanoethylation product of mesityl oxide. I

Example 6 'y-Carbozy-y-isopropyl-pimelic acld.'-A solution oi! 18 grams of KzCOa; 3.7 grams of KOH and 37 cc. of water was added to a stirred susany excess hypochlorite was destroyed by adding sodium bisulfite' solution. The resulting solution was acidified with concentrated hydrochloric acid and cooled to C. The crystalline product which separated melted at 160-16l C. after recrystallization from water or nitro-methane and was identified as -carboxy- -isopropyl-pimelic acid.

The v-acetyl-y-isopropyl-pimelic acid used as starting material is a crystalline solid, melting point 148 C., obtainable by alkaline hydrolysis of the dicyanoethylation product of methyl-isobutyldretone.

Example 7 *y-UdlbOdtQI-y-butyl-pimtlic acid .'lo a stirred, terecl solution of potassium hypochlorite prepared by treating a suspension or 125 grams of calcium hypochlorite in 500 cc. of water at 50 C. wt a solution of 88 grams of KzCOa, 25 grams of 0H, and 250 cc. of water, there was added gradually at 60-70 C. a solution of 64.5 grams of 'y-acetal-v-butyl-pimelic acid in 150 grams of aqueous 20% sodium hydroxide. chloroform was evolved. Stirring was continued one hour after reaction had apparently ceased, and any excess hypochlorite was destroyed by adding sodium bisulfite solution. Upon acidifying the solution with concentrated hydrochloric acid and cooling to (3., a white crystalline product separated, from which, by recrystallization from water, pure l-carboxy-v-butyl-pimelic acid was obtained in colorless crystals melting at 125 C.

The 'y-acetal- -butyl-pimelic acid used as starting material is a crystalline solid, melting point 60-6l C., obtainable by alkaline hydrolysis oi the dicyanoethylation roduct of methyl-narnyi ketone.

Example 8 as a colorless crystalline solid which can be recrystallized from water and melts at 114-115 C.

The -acetyl-v-amyl-pimelic acid used as starting material is a crystalline solid, melting point 73-74 C., obtainable by alkaline hydrolysis of the dlcyanoethylation product of methyl-n-hexyl ketone.

By reaction of a hypohalite. such as sodium hypobromite or hypochlorite, in alkaline solution with a compound of the formula cmon ooom a-ococrn omcmcooM wherein R is a hydrocarbon group or substituted hydrocarbon group and Mis hydrogen or a metal cation, there are formed the salts of the formula cmcmoooM.

n-o-coom CHrCHaCOOM which are readily converted to the correspondinc acid with a strong inorganic acid or an acid forming insoluble salts when M is a metal ion. The compounds in which R is an aliphatic hydrocarbon group are 03 particular importance and 0 interest.

ll claim:

1. its a new compound, a 'y-carboxy-plmelic acid having the formula CHiCHaCOOH R-C-COOH orncrnooon wherein R is an aliphatic hydrocarbon group.

2. As a new compound, a -carboxy- -lower allryl-pimelic acid.

3. As a new compound, 'y-carboxy-y-methyl- .pimelic acid.

t. as a new compound. y-carboxy- -ethylpimelic acid. 5 5. its a new compound, -carboxy /-amy1-pimelic acid.

' 6. The method of preparing -carboxy-y-aliphatic hydrocarbon substituted pimelic acid M which comprises reacting with an alkaline hypohalite solution a compound of the formula omcmoooM ra-c-coom orncmcooM wherein R is an aliphatic hydrocarbon group and M is a member of the class consisting of hydrogen and soluble salt-forming cations, and acidifying the resultant product.

HERMAN A. BRUSON. 

